The present invention relates to an image forming apparatus capable of being mounted with a sheet post-processing apparatus which conducts post-processing such as staple processing, or shift sorting processing, on a sheet ejected out of an image forming apparatus such as an electrophoto-graphic copying machine, a printer and a facsimile machine.
There is used a sheet post-processing apparatus called a finisher as an apparatus which conducts collating and stapling with a stapler for the number of sets of copies for plural recording sheets which have thereon recorded images and are ejected out of an image forming apparatus. Further, some of the sheet post-processing apparatuses have functions of shift sorting processing, collating processing, punching processing and bookbinding processing, in addition to the aforesaid staple processing.
This finisher is connected to an image forming apparatus such as a copying machine and a printer in terms of function, and it is driven in accordance with sequence operations of copy process or print process.
There is an image forming apparatus wherein a sheet ejection section is provided on the upper portion of the image forming apparatus, and a sheet having thereon formed images is ejected out of the sheet ejection section onto the top face of the apparatus to be stacked thereon, in the case of ordinary sheet ejection.
In TOKKAIHEI No. 9-309655, there is disclosed image forming apparatus 1 wherein image forming section 62 is arranged under sheet ejection section 61 and sheet-feeding section 63 is arranged under the image forming section 62, and a sheet is conveyed vertically.
Sheet S fed from sheet-feeding tray 631 of the sheet-feeding section 63 is fed to paired registration rollers 65 on sheet conveyance path 64. On the other hand, in synchronization with a toner image formed by writing unit 66 on photoreceptor drum 621 of the image forming section 62, the sheet S is conveyed from the paired registration rollers 65 to transfer section 622 where the toner image is transferred onto the sheet S. The sheet S carrying thereon the toner image is conveyed to fixing section 67 where the toner image is fixed, and then is conveyed to the sheet ejection section 61. Then, the sheet S is conveyed through horizontal conveyance path 681 of relay conveyance unit 68 provided on the upper portion of the image forming apparatus 1, to be fed into sheet post-processing apparatus FS.
The sheet post-processing apparatus FS conducts sheet post-processing such as staple processing, shift sorting and collating for the sheet S accepted by the sheet post-processing apparatus FS, and then, ejects the sheet S on a sheet ejection tray.
FIG. 7(b) shows an another example of a conventional image forming apparatus wherein sheet conveyance in an image forming section is made to be in the vertical direction. On the upper portion of image forming apparatus 1, there is mounted sorter (mail box) ST having a sheet ejection tray with four bins.
Incidentally, sheet post-processing apparatuses are already disclosed in TOKKAISHO Nos. 60-142359, 60-158463, 62-239169, 62-288002, 63-267667, TOKKAIHEI Nos. 2-276691, 8-319054 and TOKKOHEI No. 5-41991.
In image forming apparatus 1 shown in FIG. 7(a), sheet post-processing apparatus FS is connected to the side of image forming apparatus 1. Therefore, horizontal conveyance path 681 of relay conveyance unit 68 is made to be long and large and conveyance processing after sheet ejection is made to take a long time accordingly, which is a disadvantage, and sheet conveyance efficiency is lowered. Further, a housing which houses therein a staple processing section, a shift sorting processing section and a sheet intermediate stacking section (intermediate stacker section) is protruded bulkily from the side of image forming apparatus 1, which causes a disadvantage of increase in a floor space.
In image forming apparatus 1 shown in FIG. 7(b), the total height as a system is increased, because sorter (mail box) ST as a sheet post-processing apparatus is connected to the top surface of image forming apparatus 1. In particular, if an image reading device (scanner) is provided on the upper portion of image forming apparatus 1, the scanning plane of the scanner is heightened to make an operation difficult. In addition to that, the number of bins in the sorter and the number of sheets to be stacked are restricted.
An object of the invention is to correct the aforesaid disadvantage in an image forming apparatus equipped with a conventional sheet post-processing apparatus and to attain the following objects.
(1) To improve copying productivity by shortening a sheet conveyance path in the image forming apparatus and in the sheet post-processing apparatus and thereby by reducing sheet conveyance time, and to improve sheet conveyance efficiency and lower the cost by simplifying the sheet conveyance mechanism.(2) To offer a compact system by reducing the floor space of the image forming apparatus equipped with a sheet post-processing apparatus.(3) To offer a sheet post-processing apparatus capable of being provided with multi-deck sheet ejection tray (for example, sheet ejection tray with 10-20 bins) or with a movable sheet ejection tray having a long distance to go up and down on which a large number of sheets (for example, 2000 sheets) can be stacked.